Structural, microstructural and magnetic characterization of the β-CoTe nanophase synthesized by a novel mechanochemical method

This work reports an unprecedented mechanochemistry synthesis of beta-CoTe and its systematic characterization through X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), and magnetometry techniques. The mechanical alloying produced the desired material within 6 h along with minor impurities, showing good stabilization for higher milling times (15 h) and long-term storage. XRPD characterization employed the Rietveld profile fitting analysis with fundamental parameters analysis in a direct convolution approach, giving the material's structure and microstructure information. For the spherical shape, the diameter mass average of the crystallites furnished values around 13 nm with 1.1% of microstrain. The double-Voigt procedure also modeled a triaxial ellipsoid shape for the crystallite size and obtained a surface-weighted average value for its volume around 150 nm(3). TEM images confirmed the nanometric size visually and showed the crystallites to aggregate in large particles hundreds of nanometers in size. Measuring hundreds of supposed crystallite sizes, we could achieve a numerical distribution of their sizes with an average of 16 nm. The magnetization analysis performed both experimentally and via numerical simulations showed that beta-CoTe is predominantly superparamagnetic with a magnetic domain size compatible with the double-Voigt one.

Automated summary

This work successfully synthesized beta-CoTe using an unprecedented mechanochemistry method and systematically characterized it through techniques such as X-ray powder diffraction, transmission electron microscopy, and magnetometry. The material has crystallites with an average size of around 13 nm and a microstrain of 1.1%, exhibiting a triaxial ellipsoid shape. The magnetization analysis showed that beta-CoTe is predominantly superparamagnetic with a magnetic domain size compatible with the double-Voigt model.